Bromine chloride, reaction

The major organic reactions of BrCl consist of electrophilic brominations of aromatic compounds. Many aromatic compounds do not react in aqueous solution unless the reaction involves activated aromatic compounds (an example being phenol). Bromine chloride undergoes free-radical reactions more readily than bromine. 

Whilst molecular hypobromous acid can be a brominating species, it is not believed to be the active species in acetic acid solution. The bromination of 4-nitroanisole by hypobromous acid in 75 % aqueous acetic acid at 19.8 °C gave a second-order rate coefficient of 0.162, so that the brominating species here appears to be more reactive than molecular bromine194. In addition, the presence of 0.05 M sodium acetate caused the rate coefficient to fall to only 0.040, and both these observations were contrary to expectation if hypobromous acid was the brominating species, but are quite consistent with it being bromine acetate, BrOAc. Also, the addition of chloride ion caused the reaction to become immeasurably slow, due to the formation of the much less reactive bromine chloride. 

Several routes for producing bromine chloride have been examined. The reaction attains equilibrium in both the liquid and vapour phases ... 

I. Joffee, in "The Production of Bromine Chloride and Its Reactions with Olefins", DSB-BCL First Intermediate Report, March 31, (1974). 

A detailed examination of OSO4 reactions with A -steroids has been reported." The A-ring conformation of the reactant or derived complex is important in determining the stereoselectivity of these reactions, and the major role of the proximate substituents is to anchor the appropriate conformation favouring a- or /3-attack. Studies on the stereochemistry of electrophilic attack on cholest-5-en-3-one continue." As with bromine chloride," appreciable /3-attack occurs and the 5/3,6j8-epoxide was isolated along with the previously reported 5a,6a-epoxide and the Baeyer-Villiger product, the A-homo-enol lactone (58). Base-catalysed... 

A. J. Balard showed that bromic acid is decomposed by hydrobtomic add into bromine and water by hydrochloric acid into water an d bromine chloride and by hydriodic acid into water and iodine bromide. There are nine reactions belonging to this set, namely, chloric, bromic, and iodic acids each with each of the three haloid acids—HC1, HBr, and HI. The kinetics of these reactions have been studied extensively.29 W. Bray has shown that the velocity of the reaction between... 

The second piece of evidence against the mechanism of Figure 10-7 is that bromine addition reactions carried out in the presence of more than one nucleophilic reagent usually give mixtures of products. Thus the addition of bromine to an alkene in methanol solution containing lithium chloride leads not only to the expected dibromoalkane, but also to products resulting from attack by chloride ions and by the solvent ... 

The generation of HOBr can be effected by the hydrolysis of bromine gas (Br2) or liquid bromine chloride (BrCl), as in the reaction below. This type of HOBr generation requires the use of large gas cylinders and associated equipment, similar to using chlorine. It is only appropriate for large industrial process cooling systems. 

The diazo group can be replaced with chlorine or bromine by reaction with cuprous chloride or cuprous bromide. [The Cu(l) aids in the formation of the radicals that are involved in these particular reactions.]... 

In an attempt to synthesize (Z)-l,2-dihalo-l-alkenes from bromoboration adducts of 1-alkynes with B-X-9-BBN, all efforts have been unsuccessful. Fortunately, it has found that the haloboration of 1-alkynes with tribromoborane, followed by the reaction with iodine or bromine chloride in the presence of sodium acetate gives the expected (Z)-l,2-dihalo- 1-alkenes stereospecifically (>98%) in good yields (Eq. 122)187>. 

Just as bromine chloride is a more reactive electrophile than iodine chloride so one would expect bromine azide acting as an electrophile to be more reactive than iodine azide. In fact in solvents suitable for heterolytic reaction, bromine azide adds to chalcone less readily than iodine azide ° and this further indicates an Adj mechanism. The evidence is strengthened by the occurrence of acid catalysis of the bromine azide addition. 

V. Braun reaction Cyanogen bromide. Phosphorus tribromide. Piperidine. Thionyl chloride. Bromination Aluminum bromide. Aluminum chloride. Boron tribromide. Bromine chloride. N-Bromocaprolactam. N-Bromosuccinimide. Bromotrichloromethane. Cupric bromide. Dibenzoyl peroxide. l,3-Dibromo-5,5-diraethylhydantoin. 1,2-Dibromotetrachloromethane. HBr-scavengers acetamide and potassium chlorate. Iodine. Iodine monobromide. Iron. Mercuric acetate. Phenyl trimethylammonium perbromide. Phosphorus trichloride. Pyridine. Pyridine perbromide. Pyridinium hydrobromide perbromide. Silver sulfate. Sodium acetate. Sodium hypobromite. Sulfur. Sulfur monochloride. Tetramethylaramonium tribromide. M-Tribromoacetophenone. Trichloromethane sulfonyl bromide. Trilluoroacetyl hypobromite. Triphenylphosphine dibromide. 

Bromochlorination of unsaturated esters with bromine chloride both in the dark and in light has been investigated. Bromochloro- as well as considerable amounts of dibromo and dichloro adducts are formed, depending on the starting material. The regiochemistry of the bromochlorination process depends on the substrate and on the reaction conditions, a- B romo-/ -ch 1 oro esters are the preferred products from reaction in the dark and /j-bromo-a-chloro esters result from addition in light138. 

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